How to grow cannabis in coco coir
I thought id do a write-up on growing in coco coir. I was a soil grower for many years and found the aspect of PH and EC, watering daily and other things a bit daunting. When I finally made the change I was shocked at how easy it all was. Hopefully, others will get something similar from this post.
What is coco coir
Coco coir is the husk of coconuts. A waste product that turns out to be perfect for growing plants in.
The difference between soil and coco
The main difference between soil and coco is that coco is not alive in the way the soil is, you will need to give plants in coco what they need from the start and throughout their life cycle. Soil is already loaded with what a plant needs, a soil-plant will still need feeding or a prepared amended soil be used. Coco is effectively inert, you are growing in a dead nutrient-free medium. This is what makes coco so much easier in my opinion but ill get to this later. Coco plants rely on what you give them in the form of nutrients to survive, they do not get anything from coco as a medium to be grown in.
Growing in coco coir
As I've mentioned above, to grow in coco you need to give the plant everything it needs, this is what I found daunting when looking to move from soil to coco. The main staple of a plant grown in coco is base nutrients. They come in many brand names and different bottles but the idea is the same. These base nutrients contain the basic nutrients to grow a plant. I use Canna Coco A and B but as mentioned there are many different types available. These nutrients alone can grow a plant and some growers will use pretty much only base nutrients.
Coco coir needs feeding regularly, daily once roots are established. This is because of the reasons above, the coco itself cannot sustain a plant. So you as the grower will be giving the plant what it needs and doing this daily is the way most growers do things. The hidden part to this is it gives you as the grower complete control. As mentioned above, because of coco's water-holding properties you cannot overwater "within reason", so you can give your plant exactly what it needs every single day.
In order to measure what you give your plants on a daily basis, you will need certain tools. It's very important to give your plants the right amount of feed at the correct pH for the stage of growth your plant is at.
What do you need to grow cannabis in coco?
Firstly you need your coco. This comes under many brand names and prices. The 2 main differences to look at when buying coco are treated/untreated coco. Coco that comes in blocks will often need to be cleaned/flushed and treated before use, this also applies to some loose bagged coco. Be sure to research the brand and type you are buying. I personally use Canna Coco Professional, it cost a little more than standard Canna Coco but is ready to use straight out of the bag.
Next, you will need a pot, which sounds simple but in coco you are not bound by the same pot sizes as in soil. You can use smaller pots than you would in soil fir growing cannabis. This does not mean you have to. I recommend 10-15l pots as this size will cover just about any size plant a hobbyist grower will want to use. I have seen coco growers using smaller pots. As this guide is aimed at new coco growers I recommend the size above as that will only need watering once a day even in the late flower period.
Next and very important to be able to grow in coco is PH and EC pens. I will go into detail on these in a later article. The basic reason you will be needing these items is to accurately measure your feed to have it in the right range for your cannabis plants to be able to uptake the nutrients in your feed. PH and EC pens will often need calibration fluid and need to be calibrated on a regular basis.
When adding your nutrient to the water you will measure the amounts in EC or PPM. The level of EC needed will depend in the stage your plant is at. EC pens are also a great way to measure the wastewater that you get when feeding, this is a great way to see if your plants are eating and diagnose possible issues.
The nutrients within your water are only available to your plants at certain PH ranges. If you are feeding your plants a perfectly good feed solution at the wrong PH the nutrients in the feed will not be available to the plants. To high or too low and your plants may have access to certain elements in the feed but not others. It's very important to have the PH set correctly for your stage of growth.
A good rule to stick to for PH is:
Seedlings and cuttings - 5.6-5.8 PH
Veg stage 5.8-6.0 PH
Flower stage 6.0-6.2
This is not a set rule for stages of growth, some strains may be happier at slightly different PH but 99% of cannabis plants will be happy within the above numbers.
What nutrients and additives do I need to grow cannabis in coco?
First and most importantly when feeding your plants in any medium is to let the plants tell you what they want. Don't try follow a nutrient schedule or what's on the label from a company. I've been growing many years and rarely have I used the amounts stated on nutrient bottles or feed charts.
There are so many different types of nutrients and additives available to grow cannabis these days that it can become very confusing very quickly. Keep it simple and build on that grow after grow is the best advice I can give. I'll try to cover the main types of feed below.
Base nutrients:
Base nutrients supply your plants with the fundamental basic nutrients/element to grow. You can grow a plant using only base nutrients in most cases but your plants will benefit from other products being used to reach their full potential. Base nutrients come in many different brands, shapes, and sizes I recommend using a brand that has been around a long time and is cost-effective. I personally use Canna Coco A and B.
Root stimulants and microryzal products:
Root-based products have been around for a long time but a lot of research has gone into this in recent years. I'm of the belief and I recommend growers getting into coco growing to keep it simple when starting their coco journey especially when it comes to feeding. That being said I do recommend a product to promote healthy and strong root growth is used. Coco promotes fast and strong root growth so adding another layer to this aspect can only be a good thing. A product like Dynomyco is what I use and works very well with coco.
Supplements/Additives:
There are many supplemental products available to coco growers, some are not as necessary as others. The 2 I believe coco growers should have available are Cal-Mag (Calcium and Magnesium) and silicone. As mentioned above coco is an inert medium, for this reason, you may need to supplement your base nutrients to give your plants everything they need.
Cal-Mag - This can be an essential part of your feed in a number of situations. Depending on where you are in the world or if you are using RO water it may need adding to almost every feed. In other cases, depending on your water supply it may be rarely needed. Either way, this is a must-have for any coco grower. Where I am in the world my background EC is quite high meaning it has some elements available, for this reason, I do not need to add Cal-Mag often. For a grower choosing to grow in RO water, it will be part of your everyday feeding regime.
Silicone - This is something I personally do not use. It is used to promote healthy strong growth. Many growers will use this especially in the veg stage of growth so I will include it here. This is more down to the preference of the grower and does have many benefits.
PK boost:
PK Boost (phosphorus and potassium) are in my opinion an essential part of growing cannabis especially in a hydroponic growing method like coco. These are 2 elements your plants will need in flower to thrive and for you to get the most from them. Feeding PK can be tricky and you can ask 10 growers how they use PK and when and you will get 10 different answers. The basic idea with PK is that you are providing phosphorus and potassium to the plant when needed. Some growers will do this by feeding PK at different times in flower, others will feed it throughout flower, some will start feeding PK from day 1 of 12/12 other once the plants are in true flower. This is something for each grower to work out as they progress through grows. I personally feed PK throughout flower but this can itself be tricky as PK can burn plants if overused and can also age plants faster than they should. When looking at PK boosts the important part is the ratios (the numbers/levels of phosphorus and potassium contained within a bottle). Canna PK 13/14 is something I use but not continuously. I'll use this for the first 2-3 weeks of flower then use a lower ratio PK for the rest of the flower period. This is just my preference and as mentioned will differ from grower to grower.
The most important thing when using PK is not to overdo it.
Flower enhancers:
Flowering enhancers are used by many growers and come in many shapes and sizes. Do you need them to grow cannabis? No. Can they benefit your plants? Yes. Enhancers can indeed help you grow bigger flowers, some will enhance flavour and smell... But they are not essential and adding a range of nutrients to a feed schedule can cause issues of its own. If you are growing with 10 bottles of nutrients and additives and you develop an issue it can be difficult to isolate which is causing the issue. My advice to new growers is to keep it simple and build on what you know works before jumping into enhancers.
What do you actually need to grow cannabis:
As mentioned above keeping it simple when getting into coco is the best option. To grow a healthy plant from start to finish you need the basics. Its very easy to get lost in the world of shiny colorful labels and promises printed on bottles of bigger better plants but it's not needed.
Base nutrients - Something like Canna Coco A and B
Additives - Cal-Mag and Silicone
PK Boost - Something like Canna PK 13/14
You can grow using the above and you will do well.
How often should you feed/water in coco
Watering and feeding in coco is very important as you are providing everything your plant needs. The coco contains nothing unless you put it there to feed your plants. Coco is very difficult to overwater once your plants are established in the pot but first they need to become established. The trickiest part of watering and feeding in coco is the seedling stage. You don't want to much water at this stage but you also need to be providing enough to keep your young plant happy. An easy way around this is to start your plants in smaller pots and "pot up" as you go. A good rule to stick to before watering for runoff is to wait until you have roots showing out the bottom of the pot you are in. At this point, you can start watering to get the right amount of runoff. Runoff is a term used to describe the amount of water you get out of the bottom of your pot when watering your plants. In coco, you want to see 15-20% of the volume you are feeding your plants as runoff. Once your plant is established in your pot/container you will want to be feeding daily maybe even a couple of times a day in smaller pots as mentioned above. There are other benefits to this, by feeding more regularly you are putting fresh feed through your plants more often. For this reason, changing feeds, amounts of nutrients in the feed and fixing issues is much faster than growing in soil.
Flushing your plants
Flushing plants is a term you will see used a lot in hydroponic growing. It means flushing your medium/system with fresh water and is used a few ways. You can feed coco organically but in this write up and the vast majority of coco growers will be using salt-based nutrients. There is now debate around whether you do need to flush a plant at the end of flower but it's a very common practice. The purpose of flushing a plant or plants at the end of flower is to only feed them plain water to the point there are no salt-based nutrients contained within the coco and the plant is forced to start eating the stored nutrients within itself. The theory is that it's a cleaner better smoke and healthier.
The other way a flush is used is during the grow when you have an issue or want to use it as a preventative measure to stop possible issues. One of the benefits of growing in coco over soil is that should you overfeed or have another issue you can flush large amounts of water through your medium to refresh/clean it. Doing this in the soil would kill the microbial life which is essential to soil growing. You will have microbial life in coco but it's not essential to keeping a healthy plant, the feed you put in is doing that. Flushing in this way involves feeding 5 x the pot size in plain water, "flushing" the pot out. Some growers will do this around the mid of the flower period, "mid flower flush". This is to remove salt build-up that may cause issues later in the flower cycle.
My advice for new coco growers
While some of the methods and practices of growing in coco may seem a bit daunting especially if moving from soil to coco, it's really not as difficult as it seems. It involves a bit more work but you have complete control over your plants when it comes to feeding. Keep it simple and use products that have been tried and tested by others for many years. Find a system that works for you, stick to the basics, and build on them slowly grow after grow.
Coco jargon buster
Below are a few terms explained that a new coco grower may come across.
Base nutrients - Base nutrients are the basics of what your plant needs to thrive. They come in many shapes and sizes but all do a similar job, providing your plants with the essential nutrients and elements to grow.
NPK - nitrogen, phosphorus, and potassium.
PK - phosphorus, and potassium.
Flush - Flushing your plants with plain water at the end of the flower cycle or refreshing your medium by flushing 5 x the pot capacity worth of plain water.
Cal-Mag - Calcium and Magnesium.
PH - Potential of Hydrogen. This is to measure the acidity or alkalinity of your water.
EC - Electrical conductivity. This is used to measure the background or your water and to accurately measure the amount of feed to add.
PPM - Parts per million. Similar to EC, this allows you to measure the amount of feed being added.
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